Learning Objectives:
Introduction: The study aimed on evaluating the benefit of a preoperative three-dimensional (3D) planning tool for surgically placement of the bone conduction floating mass transducer (BC-FMT) of the Bonebridge (BB) bone conduction hearing implant. As the BB should be implanted in the mastoid without compromising the dura or the sigmoid sinus, placement may be challenging especially in children with small mastoids, in malformations and after multiple ear surgery.
Method: Since 2012, the Bonebridge was implanted in 22 Patients, including 7 children <16 y old (mean = 34.2 y ± 23.4 SD; min 5, max 76 y). Audiological testing was performed preoperatively, and 1 month and 3 months postoperatively. A preoperative planning tool was developed based on high resolution CT-scans of the temporal bone: AMIRA-software based 3D models of the Bonebridge implant and of the skull were freely adjusted and fusioned, allowing to detect the optimal implant position (“virtual surgery”). Transfer to the intraoperative situation was performed based on anatomical landmarks.
Results: The BB could be accurately placed in the selected locations. Simultaneous planning and implantation oft the BB and bone anchors for ear prosthesis was performed in 2 cases.In some cases, preoperative planning revealed insufficient bone thickness of the mastoid, preventing BB-implantation.Audiological data showed a significant benefit 3 months after implantation in speech recognition, hearing in noise, in directional hearing and sound localization.
Conclusions: Audiological results were comparable to those reported in other studies about bone anchored hearing systems. Preoperative 3D planning is recommended especially in primarily small, poorly pneumatized mastoids, hypoplastic mastoids in malformations, reduced bone volume after canal wall down mastoidectomy, small mastoids in children, and for planning of simultaneous implantation of bone anchors for ear prostheses.